Method and Apparatus for Performing Discontinuous Reception Operation by Connected Mode User Equipment in a Mobile Communication System

1. A method for establishing time alignment by a terminal in a mobile communication system, the method comprising: receiving, from a base station, first information for discontinuous reception (DRX) operation; monitoring a downlink control channel based on the first information; receiving, from the base station, second information for identifying a preamble on the downlink control channel; transmitting, to the base station, the preamble based on the second information; receiving, from the base station, a response message on a downlink shared channel, the response message including timing adjustment information and information for a channel quality indicator (CQI) request; establishing time alignment based on the timing adjustment information included in the response message; and transmitting, to the base station, a CQI based on the information for the CQI request.

2. The method of claim 1 , wherein the information for the CQI request comprises information on resource assignment for the CQI.

3. The method of claim 1 , further comprising: receiving downlink data from the base station after establishing the time alignment.

4. The method of claim 1 , wherein the response message further comprises an uplink grant.

5. An apparatus for establishing time alignment by a terminal in a mobile communication system, the apparatus comprising: a transceiver for receiving, from a base station, first information for discontinuous reception (DRX) operation, monitoring a downlink control channel based on the first information, receiving, from the base station, second information for identifying a preamble on the downlink control channel, transmitting the preamble based on the second information to the base station, receiving a response message that includes timing adjustment information and information for a channel quality indicator (CQI) request, from the base station on a downlink shared channel, and transmitting a CQI to the base station; and a controller operable to establish time alignment based on the timing adjustment information included in the response message and to transmit the CQI based on the information for the CQI request.

6. The apparatus of claim 5 , wherein the information for the CQI request comprises information on resource assignment for the CQI.

7. The apparatus of claim 5 , wherein the transceiver receives downlink data from the base station after establishing the time alignment.

8. The apparatus of claim 5 , wherein the response message further comprises an uplink grant.

9. A method for establishing time alignment by a base station in a mobile communication system, the method comprising: transmitting, to a terminal, first information for discontinuous reception (DRX) operation; transmitting, to the terminal, second information for identifying a preamble on a downlink control channel; receiving the preamble from the terminal; transmitting, to the terminal, a response message on a downlink shared channel, the response message including timing adjustment information for establishing time alignment and information for a channel quality indicator (CQI) request; and receiving a CQI based on the information for the COI request from the terminal.

10. The method of claim 9 , wherein the information for the CQI request comprises information on resource assignment for the CQI.

11. The method of claim 9 , further comprising: transmitting downlink data to the terminal after receiving the CQI.

12. The method of claim 9 , wherein the response message further comprises an uplink grant.

13. An apparatus for establishing time alignment by a base station in a mobile communication system, the apparatus comprising: a transceiver for transmitting, to a terminal, first information for discontinuous reception (DRX) operation, transmitting, to the terminal, second information for identifying a preamble on a downlink control channel, receiving the preamble from the terminal, transmitting, to the terminal, a response message on a downlink shared channel, and receiving a channel quality indicator (CQI) from the terminal, and a controller operable to generate the response message including timing adjustment information for establishing time alignment and information for a CQI request, and to receive the CQI based on the information for the CQI request.

14. The apparatus of claim 13 , wherein the information for the CQI request comprises information on resource assignment for the CQI.

15. The apparatus of claim 13 , wherein the transceiver transmits downlink data to the terminal after receiving the COI.

16. The apparatus of claim 13 , wherein the response message further comprises an uplink grant.